1. Field of the Invention
The present invention relates generally to shaped charge projectiles and, more particularly, is concerned with a method of assembling such projectiles that employ fluted liners.
2. Description of the Prior Art
Shaped charge projecticles have been developed to perforate the heavy armor of tanks and other combat vehicles. The shaped charge refers to a conical cavity formed in the front end of an explosive charge contained in the projectile body. The cavity is used to transform the detonation wave propagating through the explosive charge into a convergent shock wave which directs the energy of the explosion along the longitudinal axis of the cavity. Where the cavity contains a thin conical liner, the convergent shock wave causes collapse of the liner inwardly toward the cavity axis and its extrusion from the projectile as a thin, extremely high-velocity, fluid jet along the cavity axis toward the target. U.S. Pat. No. 3,948,181 to Bergstrom discloses several embodiments of shaped charge projecticles and illustrates, in a sequence of steps, the transformation of the thin conical liner into the highvelocity fluid jet for penetrating the armor of the target.
It is well-known that projectiles fired from rifled guns spin in flight and thus have greater accuracy and range than those fired from non-rifled guns. However, the penetrating power of the shaped charge jet is more fully realized when the jet does not spin during flight or, in other words, when it is fired from a nonrifled gun. In order to adapt a shaped charge projectile for use in greater-accuracy rifled weapons, it is common practice to form flutes on the liner. As explained in U.S. Pat. No. 3,726,224 to Pugh et al, the abrupt offset surfaces of the flutes face in the direction in which the projectile rotates under angular momentum imparted by the rifled gun. The offset flute surfaces impart an opposing angular momentum to the liner so that the shaped charge jet emanating from the spinning projectile does not spin and thus has a penetration power comparable or equal to that of a non-spinning projectile.
While the liner flutes have substantially obviated the deleterious effects of projectile spin on the penetration power of the shaped charge jet, they have caused difficulty heretofore in the assembly of the components of the shaped charge projectile. To assemble the projectile, typically four basic steps are involved. First, explosive propellant material, preferably in powder form, is placed in the projectile body. Next, a preformed punch is used to compress and consolidate the propellant powder and to form the conical cavity therein. Then, the fluted conical liner is placed in the cavity. And, finally, the liner is pressed into the cavity as a final consolidation of the powder is performed.
In performing the final step, care must be taken not to damage the flutes so as to adversely affect its ability to counteract the spin of the projectile. One prior art approach to accomplish this has been to provide a punch having an end with flutes formed thereon complementary to and alignable with the flutes of the liner. However, the alignment of the liner flutes with the complementary ones on the punch in an automatic assembly operation can require a great deal of mechanical motion and therefore makes the assembly operation slow and complicated.
Consequently, a need exists for a different approach to accomplishing the assembly of a shaped charge projectile employing a fluted liner. The approach should be one which eliminates the above-described alignment problem without substituting another problem in its place.